The invention relates to an improvement in the aging resistance of the sidewalls of retreaded tires. More particularly, the invention relates to a method for improving the aging resistance of the sidewalls of the retreaded tire during the retreading process.
One of the long term problems encountered by the retread tire industry has been a shortage of worn tire casings which are suitable for retreading. A significant aspect of this problem has been that the sidewalls of the worn tire generally have lower aging resistance than the sidewalls of the original tire. This often results in the sidewalls of the retreaded tire developing ozone cracking during the service life of the retreaded tire thereby making the worn tire casing unsuitable for further retreading. The problem is particularly serious in the case of truck and bus tires where the economics of truck and bus vehicle operations which includes the high cost of new tires dictate that the original tires be capable of being retreaded more than once, preferably 3 to 4 times or more.
A method of treating the surface of vulcanized rubber products which is reported to result in reduced friction coefficients and improved ozone resistance is described in Japanese patent 60108438. The method as set forth in the patent comprises treating the surface of vulcanized rubber products such as natural rubber, butyl rubber, SBR etc. with an aqueous solution of an organic active halogen compound containing--CONX --groups, wherein X is halogen, such as for example an N-haloisocyanuric acid. The treating method described in the reference involves soaking the vulcanized rubber product in the treating solution for 15-60 minutes at room temperature.